Effect of Mechanically-Induced Doping With 10 wt.% TiO2 on the Hydrogen Uptake/Release Kinetics of Commercial MgH2 Powders
Abstract
INTRODUCTIONHydrogen is an energy carrier holding tremendous promise as a clean energy option. In contrast to those traditional ways of storing hydrogen in gaseous and liquid states with their difficulties and unsafety issues,... [ view full abstract ]
INTRODUCTION
Hydrogen is an energy carrier holding tremendous promise as a clean energy option. In contrast to those traditional ways of storing hydrogen in gaseous and liquid states with their difficulties and unsafety issues, Mg and Mg-based systems have opened promising concept for storing hydrogen in a solid-state matter. However, MgH2 system reveals serious drawbacks indexed by its slow hydrogenation / dehydrogenation kinetics and high thermal stability. The present work demonstrates has been addressed in part to improve the kinetics of hydrogen gas uptake/release for commercial MgH2 powders by long term of reactive ball milling (RBM) time .
EXPERIMENTAL
Sol-gel technique was used to prepare anatase phase of TiO2 nanoparticles, used in the present work as catalytic agent for improving the hydrogenation / dehydrogenation kinetics of MgH2 powders. For the purpose of the present study, certain amount (5g) of commercial-MgH2 powders was balanced inside a helium gas atmosphere-glove box and then sealed together with forty hardened steel balls into a hardened steel vial . The vial was then filled with 50 bar of H2 gas and mounted on a high-energy ball mill operated at 250rpm. The RBM process was halted after selected time to take samples for the vial inside the glove box. The as-ball milled MgH2 powders obtained after 200h of RBM time was doped with 10 wt.% TiO2 nanoparticles and then ball-milled for 50h under hydrogen gas atmosphere.samples were characterized by means of XRD, FE-HRTEM/STEM/EDS, and FE-SEM/EDS. The thermal stability were investigated by DSC at different heating rates.
RESULTS AND DISCUSSION
Figures 1 presents the FE-HRTEM image of MgH2 powders obtained after 200h of RBM.
Figure 2 displays the STEM (a) together with the EDS elemental mapping of Mg (b) and Ti(c) for MgH2 powders milled for 200h and then ball milled with 10wt.% of TiO2 nanopowders for 50h.
Fig. 2(a) STEM of nanocomposite MgH2/10 wt. % TiO2 powders obtained after 50h of RBM.
Fig. 3 Cycle-life-time examined at 275oC for nanocomposite MgH2/10wt.
Nano composite MgH2/10 wt.% TiO2 powders revealed excellent cycle-life- time extended up to 300h at moderate temperature (275oC) with hydrogen storage capacity of 5.17wt.% H2.
Authors
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shorouq ahmed
(Kuwait Institute for Scientific Research kISR)
Topic Areas
Nanoelectronic systems, components & devices , Nanotechnology for environment and energy , Nanocatalysis & applications in the chemical industry
Session
OS1a-A » Nanotechnology for environment and energy (14:30 - Wednesday, 18th October, Auditorium)
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